There is a type of wireless communication system which includes a wireless base station and a fixed access node. The wireless base station performs a wireless communication with a user terminal. The fixed access node is connected with a higher level network at an upstream side while being connected with a wireless base station at a downstream side. Further, the fixed access node controls an access by the wireless base station to the higher level network.
According to the wireless communication system described above, only a wireless base station permitted to access by the fixed access node is allowed to access the higher level network.
In another type of wireless communication system, an access server connected with a first wireless base station transmits a healthy signal received from the first wireless base station to a second wireless base station. The healthy signal is transmitted from the first wireless base station to the access server according to the Point-to-Point Protocol (PPP). When the reception of the healthy signal from the first wireless base station is delayed, the access server transmits the healthy signal to the second wireless base station even when the healthy signal has not been received.
Further, there is a wireless communication system which measures the communication quality between a base station and a remote host. When a queue overload is detected at the remote host, the wireless communication system transmits a flow control message between the base station and the remote host. When the queue overload is detected at the base station, the wireless communication system discards packets.
Further, there is a wireless communication system which switches a communication rate between a wireless data communication card and a base station according to the amount of data communications between an electronic equipment and the wireless data communication card. A data communication according to the PPP is performed between the electronic equipment and the wireless data communication card. Further, there is a wireless communication system which estimates the communication quality and determines whether the contents need to be distributed or not based on the estimated communication quality.
Related techniques are disclosed in, for example, Japanese Laid-Open Patent Publication No. 2010-41260, Japanese Laid-Open Patent Publication No. 2003-169373, Japanese Laid-Open Patent Publication No. H11-289351, Japanese Laid-Open Patent Publication No. 2004-7601 and Japanese Laid-Open Patent Publication No. 2004-48565.
However, while various types of abnormalities may occur in the wireless communication systems described above, the wireless communication systems described above may not efficiently cope with the abnormalities.